956 D. WARD CUTLER 
membrane, thus rendering their distal ends free in the plasma ; 
subsequently they are absorbed into the body (Text-fig. 3). The 
actual divisions of the centroblepharoplast takes place exceed- 
ingly rapidly, and I have not seen the intermediate phases. 
It seems probable, however, that the splitting originates at 
the posterior end and travels forwards, for in a good many 
animals the basal region is double, but the anterior one still 
single, though obviously much thicker than normal. At 
the completion of division the plasma lying between the two 
centroblepharoplasts splits, leaving a clear space which is 
TEXT-FIG. 4. 
Dividing nucleus with the chromatin in the form of a loose spirene. 
x 1,250; sae; HH. 
probably the initiation of division of the animal into two 
(Text-fig. 3). The whole process recalls that described by Kofoid 
and Swezy in T. campanula, and the incomplete descrip- 
tion given by Hartmann for his male form of T. hertwigi; 
a paradesmose, however, 1s not formed between the daughter 
centroblepharoplasts in P. pristina., As already men- 
tioned, the resting—non-dividing—nucleus is composed of large 
irregular clumps of chromatin. At the onset of division these 
chromatin blocks break up into a number of small rounded 
granules embedded in a matrix (‘Text-fig. 8). Soon the granules 
become arranged to form a long spireme, and at this stage the 
clear space between the membrane and the chromatin dis- 
appears (‘l'ext-fig. 4). The nuclear membrane, however, remains 
